Novel four-wheel drive transmission system

Abstract

A novel four-wheel drive transmission system comprises a left front wheel, a right front wheel, a left rear wheel, a right rear wheel, power sources, speed reducers and a battery, the left front wheel is fixedly connected with the left front power source through a front speed reducer, and the right front wheel is fixedly connected with the right front power source through the front speed reducer. The left rear wheel is fixedly connected with the left rear power source through the rear speed reducer, the right rear wheel is fixedly connected with the right rear power source through the rear speed reducer, the left front power source and the right front power source are electrically connected with the front MCU, and the left rear power source and the right rear power source are electrically connected with the rear MCU. The front MCU and the rear MCU are respectively and electrically connected with the battery, the front speed reducer and the rear speed reducer are respectively and electrically connected with the VCU, the VCU exchanges data with the front MCU, the rear MCU and the battery through CAN-bus bus communication, and a BMS battery management system on the battery respectively exchanges data with the front MCU and the rear MCU through CAN-bus bus communication.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicles, and in particular to a novel four-wheel drive transmission system. Background Art

[0002] At present, most of the new energy vehicles adopt centralized drive mode, that is, one set of power source drives two wheels (two-wheel drive) or even four wheels (four-wheel drive), and is designed with a mechanical differential. If one side of the wheel slips, the other side will have no power output, so there are inherent defects in power distribution and escape ability. With the rapid development of new energy vehicles, the pursuit of ultimate sportiness and handling, better safety and escape ability has gradually led to the emergence of a new transmission system, namely distributed drive: a set of power sources independently drives one wheel, there is no mechanical differential, the left and right wheels are independently controlled, and the differential between the wheels is achieved through software control; the specific structure has various forms depending on the spatial arrangement of the power source and the reducer, but the functional advantages are the same, with excellent sportiness and handling characteristics, a smaller turning radius, a higher cornering speed, and anti-slip control of the drive wheels. At the same time, it has better safety performance, can quickly avoid obstacles, and has better driving stability.

[0003] Distributed drive uses the driving force of the electric drive system to steer the vehicle, thereby improving the stability of the vehicle. However, due to the torque characteristic limitation of the driving power source, especially under high-speed conditions, the driving torque and power generation torque of the power source are very small, so the vehicle yaw moment generated by the power source is very small, that is, the electric drive system of the central distributed drive vehicle has little effect on improving the vehicle's handling stability under high-speed conditions.

[0004] In order to further improve the handling stability of central distributed drive vehicles under high-speed conditions, there are generally two existing solutions. One is to increase the power source power, but increasing the power source power will lead to excessive power redundancy in the power system, which is not conducive to cost reduction and miniaturization of the drive system; the other is to compensate for the back-drag torque of the drive system through the braking function of the chassis ESC system, which generates a larger yaw torque with the forward-driven power source torque to obtain good handling stability under high-speed conditions. However, since the ESC system involves the safety performance of the vehicle, ESC suppliers are reluctant to open up corresponding permissions. Summary of the invention

[0005] The purpose of the present invention is to provide a novel four-wheel drive transmission system to address the corresponding deficiencies of the prior art. The four-wheel drive transmission system can further improve the handling stability of a central distributed drive vehicle without increasing the power of the power source and without involving an ESC system.

[0006] The objective of the present invention is to adopt the following scheme to achieve: a new four-wheel drive transmission system, including a left front wheel, a right front wheel, a left rear wheel, a right rear wheel, a power source, a reducer and a battery, the left front wheel is connected and fixed to the left front power source through a front reducer, the right front wheel is connected and fixed to the right front power source through a front reducer, the left rear wheel is connected and fixed to the left rear power source through a rear reducer, the right rear wheel is connected and fixed to the right rear power source through a rear reducer, the left front power source and the right front power source are electrically connected to the front MCU respectively, the left rear power source and the right rear power source are electrically connected to the rear MCU respectively, the front MCU and the rear MCU are electrically connected to the battery respectively, the front reducer and the rear reducer are electrically connected to the VCU vehicle controller respectively, the VCU vehicle controller exchanges data with the front MCU, the rear MCU and the battery through CAN-bus bus communication, and the BMS battery management system on the battery exchanges data with the front MCU and the rear MCU respectively through CAN-bus bus communication.

[0007] The left front wheel and the right front wheel are transmission connected to the front reducer, the left front power source and the right front power source are transmission connected to the front reducer, the left rear wheel and the right rear wheel are transmission connected to the rear reducer, and the left rear power source and the right rear power source are transmission connected to the rear reducer.

[0008] The front MCU, the left front power source, the right front power source and the front reducer are arranged in an electric drive assembly.

[0009] The rear MCU, the left rear power source, the right rear power source and the rear reducer are arranged in an electric drive assembly.

[0010] The input shafts of the front reducer and the rear reducer are provided with friction reduction devices.

[0011] The front reducer and the rear reducer are both arranged in parallel with a single gear and three shafts.

[0012] The two power sources of the front axle and the rear axle of the transmission system are parallel-axis centrally distributed.

[0013] The data transmitted by the VCU vehicle controller and the BMS battery management system on the battery through CAN-bus communication include power source speed, power source torque, accelerator pedal size, steering wheel angle, brake pedal status, requested power source torque, reducer input shaft speed, and vehicle speed information.

[0014] The left front power source and the front reducer drive the left front wheel independently, and the right front power source and the front reducer drive the right front wheel independently.

[0015] The left rear power source and the rear speed reducer drive the left rear wheel independently, and the right rear power source and the rear speed reducer drive the right rear wheel independently.

[0016] The advantages of the present invention are that the four-wheel drive system has four power sources, two power sources for the front axle and the rear axle are parallel-axis centrally distributed to drive the wheels, the power sources are arranged on both sides, the reducer adopts a single-speed three-axis parallel arrangement, and a set of separately controlled reducers is added to the input shaft. Combined with the drive and brake integrated control module in the VCU, the brake monopoly control authority of the ESC is broken away, and the handling stability of the vehicle is improved while maintaining the longitudinal acceleration performance; according to different working conditions, the VCU vehicle controller parses the vehicle's required torque according to the driver's throttle, brake and steering signals and the four power source maps, and then transmits the parsed vehicle's required torque to the CAN-Bus. The torque on the front axle is controlled by the front MCU and distributed to the left front power source and the right front power source, and the torque is transmitted to the left front wheel and the right front wheel through the front reducer. The torque on the rear axle is controlled by the rear MCU and distributed to the left rear power source and the right rear power source, and the torque is transmitted to the left rear wheel and the right rear wheel through the rear reducer. The four power sources independently control the power output of the four wheels. At the same time, according to the ideal posture requirements of the whole vehicle, the drive and brake integration module in the VCU outputs the braking signal to the brake actuators in the front reducer and the rear reducer, thereby optimizing the vehicle's yaw torque and realizing complex functions such as acceleration, steering and escape from difficulties. At the same time, it can also greatly improve the economy and handling stability of the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the transmission system structure of the present invention; Figure 2 It is intended to extend the external characteristics of the power source that can be achieved by the transmission system of the present invention. DETAILED DESCRIPTION

[0018] like Figure 1As shown, a novel four-wheel drive transmission system includes a left front wheel 13, a right front wheel 11, a left rear wheel 8, a right rear wheel 6, a power source, a reducer and a battery 15. The left front wheel 13 is connected and fixed to the left front power source 14 through the front reducer 12, the right front wheel 11 is connected and fixed to the right front power source 10 through the front reducer 12, the left rear wheel 8 is connected and fixed to the left rear power source 7 through the rear reducer 7, and the right rear wheel 6 is connected and fixed to the right rear power source 5 through the rear reducer 7. The left front power source 14 and the front reducer 12 drive the left front wheel 13 separately, and the right front power source 10 and the front reducer 12 drive the right front wheel 11 separately. The left rear power source 9 and the rear reducer 7 drive the left rear wheel 8 separately, and the right rear power source 5 and the rear reducer 7 drive the right rear wheel 6 separately. The left front power source 14 and the right front power source 10 are electrically connected to the front MCU3 respectively to transmit UVW signals. The left rear power source 8 and the right rear power source 5 are electrically connected to the rear MCU4, respectively, to transmit UVW signals. The front MCU3 and the rear MCU4 are electrically connected to the battery 15, respectively, to transmit UVW signals. The front reducer 12 and the rear reducer 7 are electrically connected to the VCU vehicle controller 1, respectively, to transmit UVW signals. The VCU vehicle controller 1 exchanges data with the front MCU3, the rear MCU4 and the battery 15 through CAN-bus bus communication, and the BMS battery management system 2 on the battery 15 exchanges data with the front MCU3 and the rear MCU4 through CAN-bus bus communication. The data includes: power source speed, power source torque, accelerator pedal size, steering wheel angle, brake pedal status, requested power source torque (including torque reduction and torque increase), reducer input shaft speed, vehicle speed information (longitudinal and lateral), etc. The left front wheel 13 and the right front wheel 11 are connected to the front reducer 12 by transmission, the left front power source 14 and the right front power source 10 are connected to the front reducer 12 by transmission, the left rear wheel 8 and the right rear wheel 6 are connected to the rear reducer 7 by transmission, and the left rear power source 9 and the right rear power source 5 are connected to the rear reducer 7 by transmission. The deceleration device inside the reducer is arranged on the input shaft, and its principle is contact friction deceleration. Its deceleration pressure plate is fixedly connected to the reducer housing, and the driven plate is fixedly connected to the input shaft. It is driven by hydraulic drive, and the pressure plate is pressed to make it contact with the driven plate to generate friction deceleration. The front MCU3, the left front power source 14, the right front power source 10 and the front reducer 12 are arranged in an electric drive assembly, and the rear MCU4, the left rear power source 9, the right rear power source 5 and the rear reducer 7 are arranged in an electric drive assembly. The input shafts of the front reducer 12 and the rear reducer 7 are provided with friction deceleration devices controlled by electro-hydraulic. The front reducer 12 and the rear reducer 7 are both arranged in parallel with a single gear and three shafts. The two power sources of the front shaft and the rear shaft of the transmission system are centrally distributed in parallel shafts.

[0019] The following is the working process of the drive system under various working conditions: When the vehicle is driven straight, the VCU vehicle controller 1 analyzes the driver's intention and calculates the total required driving torque. According to the power source torque limit, power source external characteristic limit, battery maximum charge and discharge power limit and optimal driving efficiency algorithm, the optimal torque distribution coefficient and the required torque and speed of the four power sources can be obtained. The signal is transmitted to the front MCU3 and the rear MCU4 to control the left front power source 14, the right front power source 10, the left rear power source 9, and the right rear power source 5 to transmit the torque output to the front reducer 12 and the rear reducer 7, and finally to the four wheels. When driving straight, the torque of the power sources on the left and right sides is equal, and the speed of the four power sources is equal.

[0020] When the vehicle brakes, the VCU vehicle controller 1 analyzes the brake pedal signal and the master cylinder pressure signal, and calculates the required regenerative braking force of the front and rear axle power sources based on the composite braking strategy and constraints such as the power source, battery and vehicle speed. The signal is transmitted to the front MCU3 and the rear MCU4 to control the left front power source 14, the right front power source 10, the left rear power source 9, and the right rear power source 5 to transmit the torque output to the front reducer 12 and the rear reducer 7, and finally to the four wheels.

[0021] When the vehicle is turning and driving, the gear signal is D gear, the accelerator pedal opening is greater than 0, the vehicle speed is greater than the maneuverability intervention threshold speed, and the steering wheel angle absolute value is greater than the maneuverability intervention threshold angle when the maneuverability control conditions are met. The VCU vehicle controller 1 enters the maneuverability control module and calculates the required yaw rate and yaw moment according to the ideal vehicle trajectory of maneuverability. If the vehicle turns left, the torque and speed of the left power source are less than the torque and speed of the right power source. Similarly, if the vehicle turns right, the torque and speed of the right power source are less than the torque and speed of the left power source. If the vehicle pursues the ultimate maneuverability, that is, the actual running trajectory of the vehicle follows the ideal trajectory as much as possible, then the yaw moment will be relatively large, especially when driving at high speed. However, when driving at high speed, the speed of the power source is high, the torque of the power source in the constant power range is small, and the yaw moment level formed by the positive driving power source torque and the negative "braking" power source generating torque is small. Therefore, in order to achieve a larger yaw moment when the vehicle is driving at high speed, the VCU vehicle controller 1 calculates the braking force signal and transmits it to the deceleration device actuators in the front decelerator 12 and the rear decelerator 7, thereby realizing the negative torque superimposed on the "braking torque" of the deceleration device on the basis of the external characteristics of the power source, forming an extension of the external characteristics of the power source as shown in the attached figure. Figure 2 As shown, the yaw moment of the vehicle under high speed conditions is increased. The technology for increasing the yaw moment formed by the combined torque of the driving torque of the power source and the negative torque of the power source superimposed on the "braking torque" of the reduction device is called the drive-brake integration technology. The drive-brake integration technology can be applied to the full speed range of the vehicle to provide the vehicle with better handling stability performance.

[0022] When the actual vehicle trajectory feedback shows that the lateral acceleration is too large or the vehicle speed is too high, the VCU vehicle controller 1 enters the stability control module, calculates the required yaw angular velocity and yaw moment according to the ideal vehicle trajectory for stability, and calculates the required torque of the four power sources according to the yaw moment. The signal is transmitted to the front MCU3 and the rear MCU4 to control the left front power source 14, the right front power source 10, the left rear power source 9, and the right rear power source 5 to transmit the torque output to the front reducer 12 and the rear reducer 7, and finally to the four wheels.

[0023] When the vehicle slips, the tires begin to slip, and the VCU vehicle controller 1 enters the drive anti-skid control module to estimate the longitudinal and lateral adhesion coefficients of the road surface, and then calculates the control torque under the slip state. For example, the left front wheel 13 slips, and the left front power source 14 requires the torque to be reduced to the control torque to avoid wheel slip. The driving force of each tire can be controlled individually to improve the stability of the vehicle. The control torque signal is transmitted to the front MCU3 and the rear MCU4 to control the left front power source 14, the right front power source 10, the left rear power source 9, and the right rear power source 5 to transmit the torque output to the front reducer 12 and the rear reducer 7, and finally to the four wheels.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A novel four-wheel drive transmission system, comprising a left front wheel (13), a right front wheel (11), a left rear wheel (8), a right rear wheel (6), a power source, a reducer and a battery (15), characterized in that: The left front wheel (13) is connected and fixed to the left front power source (14) via the front reducer (12), the right front wheel (11) is connected and fixed to the right front power source (10) via the front reducer (12), the left rear wheel (8) is connected and fixed to the left rear power source (7) via the rear reducer (7), the right rear wheel (6) is connected and fixed to the right rear power source (5) via the rear reducer (7), the left front power source (14) and the right front power source (10) are respectively electrically connected to the front MCU (3), the left rear power source (8) and the right rear power source (5) are respectively electrically connected to the rear The front MCU (3) and the rear MCU (4) are electrically connected to the battery (15), the front reducer (12) and the rear reducer (7) are electrically connected to the VCU vehicle controller (1), the VCU vehicle controller (1) exchanges data with the front MCU (3), the rear MCU (4) and the battery (15) via CAN-bus communication, and the BMS battery management system (2) on the battery (15) exchanges data with the front MCU (3) and the rear MCU (4) via CAN-bus communication.

2. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The left front wheel (13) and the right front wheel (11) are in transmission connection with the front reducer (12); the left front power source (14) and the right front power source (10) are in transmission connection with the front reducer (12); the left rear wheel (8) and the right rear wheel (6) are in transmission connection with the rear reducer (7); and the left rear power source (9) and the right rear power source (5) are in transmission connection with the rear reducer (7).

3. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The front MCU (3), the left front power source (14), the right front power source (10) and the front reducer (12) are arranged in an electric drive assembly.

4. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The rear MCU (4), the left rear power source (9), the right rear power source (5) and the rear reducer (7) are arranged in an electric drive assembly.

5. The novel four-wheel drive transmission system according to claim 1 is characterized in that: A friction reduction device is provided on the input shafts of the front reducer (12) and the rear reducer (7).

6. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The front reducer (12) and the rear reducer (7) both adopt a single-speed three-axis parallel arrangement.

7. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The two power sources of the front axle and the rear axle of the transmission system are parallel-axis centrally distributed.

8. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The data transmitted by the VCU vehicle controller (1) and the BMS battery management system (2) on the battery (15) via CAN-bus communication include power source speed, power source torque, accelerator pedal size, steering wheel angle, brake pedal status, requested power source torque, speed of the reducer input shaft, and vehicle speed information.

9. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The left front power source (14) and the front reducer (12) independently drive the left front wheel (13), and the right front power source (10) and the front reducer (12) independently drive the right front wheel (11).

10. The novel four-wheel drive transmission system according to claim 1 is characterized in that: The left rear power source (9) and the rear reducer (7) independently drive the left rear wheel (8), and the right rear power source (5) and the rear reducer (7) independently drive the right rear wheel (6).

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